Commonly used messaging services include Short Message Service (SMS), Multimedia Messaging System (MMS), Email Service, Instant Messaging (IM) Service, etc. Although these messaging services are provided based on different technologies, they overlap one another in many aspects in the light of user experiences. For example, all of these messaging services can send text messages, and the services other than SMS can also send multimedia content.
Considering the overlapping of the user experiences, Open Mobile Alliance (OMA) has recently defined a new service called Converged IP Messaging service (CPM service) based on a Session Initiation Protocol (SIP) and an Internet Protocol (IP). The CPM service is aimed to provide key features of the existing messaging services in a single messaging service. Accordingly, by simply using the CPM service, a user can experience the user services that all the existing messaging services have provided, and can also exchange messages with users of all the existing messaging services.
A schematic configuration of a system supporting the CPM service is shown in FIG. 1. Referring to FIG. 1, the CPM system includes a CPM client 10, an Interworking Function (IWF) 20, a message/media storage 30, a converged address book 40, a user preference storage 50, a CPM server 60, and a SIP/IP core network 70.
The CPM client 10 is generally included in a terminal, and provides interfacing between a CPM service and a user. In other words, the CPM client 10 serves to handle requests of the user. For example, if the user creates content and requests delivery of the content, the CPM client 10 converts this content to be suitable to the CPM service, includes the converted content in a SIP MESSAGE, and sends the SIP MESSAGE to the SIP/IP core network 70. Also, the CPM client 10 receives content sent from another client, determines and verifies whether the content has been correctly received, and if so delivers the received content to the user. Thus, the CPM client 10 may be considered as a contact point between the user and the CPM service.
The CPM server 60 is a server that handles the requirements the CPM client 10 sends through a CPM conversion interface. The CPM server 60 applies the policy set by the service provider or the user to the CPM contents provided from the CPM client 10.
The IWF 20 converts CPM content and provides it to another messaging service so that the message content delivered by a sending CPM client, i.e., the CPM content, may be processed by another messaging service other than the CPM service. Also, upon receiving content of another messaging service, the IWF 20 converts a format of the content so that the content may be processed by the CPM service. This operation of the IWF 20 is called interworking. The IWF 20 is connected to the CPM server 60 through a CPM-IW interface, and connected to other messaging services through interfaces provided by those messaging services.
The message/media storage 30 serves to store messages delivered to the user in the absence of the user or depending on user's settings. The converged address book 40, a kind of phonebook, includes a contact list and serves to insert presence information into information about each contact and provide the contact information to the user.
The SIP/IP core network 70, a low-level network supporting necessary SIP and IP, exists between all of the above-described components and is responsible for routing all messages. An example of the SIP/IP core network 70 includes an IP Multimedia Subsystem (IMS).